Oscar Reutersvärd

Swedish artist OSCAR REUTERSVÄRD is being considered as "father" of impossible figure.
He created the first impossible triangle out of a series of cubes in 1934. For years of painting he had created more than 2500 impossible figures. All of his figures are represented in parallel (japanese) perspective in it's puriest form only with blocks.

found via http://butdoesitfloat.com/